Dash-pot.



DASH POT.

APPLIGATION FILED NOV. 6, 1911. 1,058,290. Pat nted Apr. 8, 1913.

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. 1 FIG. 4 L HHHHHHIW .mIlHIHHIHIW" 11 IL IN VENTOR I/ I QF'M m- WITNESSES UNITED STATES PATENT OFFICE.

FRED B. COREY, OF EDGEWOOD PARK, PENNSYLVAN IA, AS SIGNOR,.BY MESNE ASSIGN- MENTS, '10 UNION SWITCH & SIGNAL COMPANY, A CORPORATION OF PENN- SYLVANIA.

DASH-POT Specification 01' Letters Patent.

Application filed November 1911. Serial No. 658,651.

wood Park, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Dash- Pots, of whiclrthe'folldwing is a specification.

My invention relates to dash pots of the type comprising a cylinder and a piston, the cylinder containing a fluid which retards the relative movement of the two.

I will describe one form of dash pot embodying my invention and then point out the novel features thereof in claims.

In the accompanying drawings, Figure 1 is a view showing in vertical section one form of dash pot embodying my invention. Figs. 2 and 3 are views showlng more clearly two of the members comprised in the dash 0t shown in Fig. 1. Fig. 4 is a viewshowmg in its developed form the member illustrated in Fi 3.

Similar re erence characters refer to similar parts throughout the several views.

One feature of my invention is the provision of means for renderin the operation of the dash pot constant at al temperatures. I accomplish this feature by means of a port 10 designates a cylin 1 elevation in Fig. 2. The cylinder contains a suitable-fluid for the purpose of retarding the movement of the piston; in the practice of my invention this fluid. is preferably oil, although I do not wish' to limit myself to any particular fluid. 16 is a piston ring, of v a usual type carried b the piston for pre-' 46 venting the escape of t e fluid past the sides of the piston. The piston 11 is rovided with a port 13 throu h which the uid may flolyv from either si e of the piston to the ot er.

Owing to the variations of the fluidity of oil with variations of temperature, it is ap-- parent that with the apfparatus as thus far escribed the velocity 0 relative movement of the piston and cylinder (with a given force on the piston rod 12 or on the cylinthrough thepiston of the-dash pot, and a.

Referring now to 1 of the drawings,- er and 11 a piston movable therein. The piston '11 is shown in der) would vary with the temperature, the velocity being relatively hi h with a high temperature and relatively Iow with a low temperature. In order to render this velocity constant for all temperatures, I provide means for varying the areaof the port .13 in accordance with the temperature so that the area will be less for a high temper? ature and greater for a low temperature. As here shown this means comprises a metallic ring 14 located within a suitable chamber in the piston. This ring is shown in per-' spective in Fig. 3. One end of the ring is rigidly secured to the piston, as for example by means of a screw 15, and the other end is free and terminates over the port 13. In the practice of my invention, the piston is referably of castiron, which. has a relatively low co-eflicient of expansion, and the ring is preferably of brass, which has'a relatively high co-eficient of expansion. -It will be clear that-as the ,tem erature increases, the

Patented Apr. 8, 1913.:

length of the rin 14 Increases more rapidly thanthe circum erence of the'piston chamber and the free end covers more of the port 13, thereby reducing the area, of the port; and as the temperature decreases the length of the ring decreases more ra idly than the circumference of the piston 0 am ber and the free end covers less of the port,

thereby increasing the area of the port. The

area of the port and the length of the ring can'be so adjusted thatfor any temperature withinreasonable limits the velocity of the relative movement of the piston and cylinder will be substantially constant.

.As shown" in the accompanying drawing the ring 14 is peculiarly shaped so thatitmakes two complete turns within a minimum amount of space. The developed form of this ring is shown in.Fig. 4. I do not wish however to be limited to this particular shape of ring, or to this particular number of turns.

The dash pot as this far described is double actingthat is, the retardation is equal for a relative movement of the piston and cylinder in either direction. It' is sometimes desirable however that the, relative movement in one direction should be com-. paratively free, and when this is the case the piston may be provided with a suitable check valve arranged to permit the passage of fluid in one direction but not in the other. I have shown one form of check valve in a suitable valve seat in this passage. The

ball is prevented from falling out by means of a pin 19. The arrangement ,is such that when the piston is-moving downwardly with respect to the cylinder theball is seated, and the flow of fluid through the passage 17 is prevented; but when the movement is inthe opposite direction the ball is unseated and fluid flows freely through the passage 17.

Although I have herein shown and described only one form of dash 'pot embodying my invention, it is understood that various modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my. invention, what I claim is- 1. In a dash pot, a cylinder, apiston therein, a port through the piston, and a member responsive to variations of temperature, one portion of which is rigidly secured to the piston and another portion of which partial y covers thesaid port.

2. In a dash pot, a cylinder, a piston therein, a port through the piston, and a me-' tallic ring comprising a plurality of turns,

one end of which is secured to the piston. and the other end of which terminates over the said port.

3. In a dash therein, a port rough the piston and a member responsive to variations of temperature one portion of which is secured to the piston and another portion of which partially covers the said portwhereby the area of the port will be increased or decreased plot, a cylinder, a piston t through the pistonfor the passage of the fluid, and a member one portion of which is secured to the piston and another portion of which is free and terminates over the port, the piston and the said member having difli'erent co-efiicients of expansion.

5. In a dash pot, a cylinder, a piston therein, a ,fluid in the cylinder, 2. port through the piston for'the passage of the fluid, and a ring one end of which is secured to the piston and the other end of which is freeand terminates over the port, the piston and the ring having difl'erent co-efiicients of expansion.

6. In a dash pot, a cylinder, a' piston therein, a cup-shaped recess in one face of the piston, a port connecting said recess with the other face, and a ring located in said recess one end of which is secured to the piston and the other end of which is 'free and terminates over the port, the piston In a dash pot, a cylinder, a pistonv therein, a port through the piston, and

means responsive to variations of tempera-- ture for controlling said port, one portion of which isrigidly secured to the piston and another portion ofwhich partially covers the said port.

In'testimon whereof I afiixmy signature in presence 0 two witnesses.

. FRED B. COREY. Witnesses:

G. J. SCHREUDER, A. L. VENOILL. 

